Environment aware business delegates

ABSTRACT

A method, system and apparatus for an environment aware business delegate. A method for delegating an invoked action in an enterprise application can include determining an environment from which the action has been invoked and selecting a behavior for use which corresponds to the environment. Subsequently, the action can be delegated to the selected behavior for processing in the enterprise application. In a specific aspect of the invention, the determining step can include determining whether the action has been invoked in a server, in an online client or in an offline client.

BACKGROUND OF THE INVENTION

1. Statement of the Technical Field

The present invention relates to the field of enterprise computing andmore particularly to the use of delegate logic to separate program logicfrom presentation logic in an enterprise application.

2. Description of the Related Art

Traditional client server application mix presentation and businesslogic in the client tier while the server tier provides backend datastorage and server side business logic. Consequently, client serverapplications typically cannot scale within the enterprise given thedifficulty in maintaining both the client tier and the server tier.Specifically, changes to the presentation layer of an applicationrequire the modification of the client side application which can impactthe integrity of the business logic within the client tier. Similarly,changes to the business logic of the client can jeopardize the integrityof the presentation code in the client tier. Developing for the clienttier also can be problematic where logic developers further develop thepresentation layer, or where human factors designers develop for thelogic layer of the application in the client tier.

To force a separation of the presentation and logic layers as ispreferred among contemporary computer scientists, server pagetechnologies have become the preferred vehicle for multi-tierapplication. Server page technologies release the client tier from theresponsibility of processing logic for rendering the presentation layer.Moreover, server pages largely separate presentation layer logic fromthe static elements of the presentation layer so that user interfacedesigners can perform changes to the static elements of the presentationlayer without breaching the integrity of the programmatic elements ofthe presentation layer.

Notwithstanding, presentation-tier components often directly interactwith business logic. The direct interaction between the presentationtier can expose the underlying implementation details of the applicationprogramming interface (API) for the business logic to the presentationtier. As a result, the presentation tier components can becomevulnerable to changes in the implementation of the business logic.Specifically, when the implementation of the business logic changes, sotoo must the exposed implementation code in the presentation tier.

Also, network performance can be affected when presentation tiercomponents directly interact with business logic because intermediatecaching or aggregating can be absent from the equation. Lastly, anexposed API to the business logic can force the client to directly dealwith networking issues associated with the distributed nature of beantechnologies. Consequently, the business delegate model has beenproposed to inject and intermediary between the presentation tier andthe business logic of an enterprise application.

In the business delegate model, a business delegate acts as aclient-side business abstraction providing an abstraction of theimplementation of the underlying of the business logic. Therefore, usinga business delegate reduces the coupling so that clients can be shieldedfrom the possible volatility in the implementation of the business logicAPI. In particular, when the business logic API or underlying businesslogic changes, the number of changes required in the presentation tieror other tiers which utilize the business delegate can be minimized. Asyet an additional advantage, the business delegate can cache results andreferences to remote business logic thereby improving networkperformance.

Nevertheless, the business delegate model is not without its ownchallenges. For one, in many enterprise applications the business logicof the enterprise application can be invoked from a variety of differenttypes of environments. These disparate environments can range from theserver environment to a remote client environment, to a remote, off-lineclient environment. The preferred behavior of a business delegate canvary based upon from which environment the business logic has beeninvoked. Yet, the business delegate model does not permit a variabilityin behavior and assumes a single behavior regardless of callingenvironment.

SUMMARY OF THE INVENTION

The present invention addresses the deficiencies of the art in respectto the business delegate model and provides a novel and non-obviousmethod, system and apparatus for an environment aware business delegate.In this regard, a method for delegating an invoked action in anenterprise application can include determining an environment from whichthe action has been invoked and selecting a behavior for use whichcorresponds to the environment. Subsequently, the action can bedelegated to the selected behavior for processing in the enterpriseapplication. In a specific aspect of the invention, the determining stepcan include determining whether the action has been invoked in a server,in an online client or in an offline client.

The selecting step can include mapping the determined environment to acorresponding behavior specified by a profile in a descriptor file in anarchive hosting a delegate for the action. The delegating step, bycomparison, can include delegating the action to a method associatedwith the selected behavior, where the method references a service forthe determined environment. Alternatively, the delegating step caninclude delegating the action to a method associated with the selectedbehavior where the method references one a service, such as anenterprise bean service or a plain object service. In any case, themethod finally can include the step of performing one of pre-processingand post-processing of a result produced by the selected behavior. Thepre-processing and post-processing, for example, can include a cachingof the result.

An environment aware business delegate archive can include at least onedelegate and at least one service. The delegate can reference at leastone behavior corresponding to a particular environment specified in anassociated referenced profile. The service, by comparison, can define aninterface to at least one environment specific service. Finally, thebehavior can have at least one association with a method correspondingto the at least one environment specific service. Preferably, thearchive also can include a descriptor file specifying different bindingsof delegates to different behaviors based upon different invocationenvironments.

Additional aspects of the invention will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The aspectsof the invention will be realized and attained by means of the elementsand combinations particularly pointed out in the appended claims. It isto be understood that both the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute partof this specification, illustrate embodiments of the invention andtogether with the description, serve to explain the principles of theinvention. The embodiments illustrated herein are presently preferred,it being understood, however, that the invention is not limited to theprecise arrangements and instrumentalities shown, wherein:

FIG. 1 is a schematic illustration of an enterprise system adapted foruse with environment aware business delegates; and,

FIG. 2 is an object diagram illustrating an architecture for enterpriseaware business delegates in accordance with the inventive arrangements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a method, system and apparatus forenvironment-aware business delegates. In accordance with the presentinvention, a business delegate model can be expanded to allow for theloose coupling of individual methods of a delegate to one or moreservices. The coupling can have different defined behaviors dependingupon where the delegate has been invoked and the state of theenvironment in which the delegate has been invoked. For instance, theenvironment can include server hosted, client hosted and on-line, orclient hosted and off-line environments, to name three suchenvironments. The loosely coupled definitions also can includeinvocation characteristics on a method level, such as caching or methodavailability, depending upon the environment. Notably, the coupling canbe accomplished by way of a descriptor file disposed within an archivefor the delegate.

In further explanation, FIG. 1 is a schematic illustration of anenterprise system adapted for use with environment aware businessdelegates. The system can include one or more client computing platforms120 coupled to a server computing platform 110 over a computercommunications network 130. The server computing platform 110 can beconfigured to host an enterprise application 190 as can selected ones ofthe client computing platforms 120.

When hosted in the server computing platform 110, the enterpriseapplication 190 can permit user interface interactions with one or moreof the client computing platforms 120. By comparison, when hosted in aclient computing platform 120, the application can permit user interfaceinteractions within the client computing platform 120. Notably, theclient computing platform 120 can host the enterprise application 190either in an on-line state where interactions with the server computingplatform 110 can support aspects of the operation of the application190, or an off-line state where the server computing platform 110 cannotsupport aspects of the operation of the application 190.

The enterprise application 190 can include both a presentation tier 180and a business logic tier (not shown). As part of the business logictier, a delegate architecture can be implemented through the coupling ofa delegate archive 140 to the presentation tier 180. It is to beunderstood, however, that the delegate archive 140 is not limited foruse by the presentation tier 180 and the delegate archive 140 can beutilized by other services for inter-services communication as well. Inany case, the delegate archive 140 can include one or more delegates tounderlying logical methods 160 in the business logic. The choice oflogical methods when responding to interactions in the presentation tier180 can be controlled by a behavioral definition 150 which can bespecified within a descriptor file in the delegate archive 140.

Importantly, a dynamic proxy 170 can consult the behavioral definition150 when creating an instance of a delegate according to the environmentin which the delegate has been invoked. In more particular explanation,FIG. 2 is an object diagram illustrating an architecture for enterpriseaware business delegates in accordance with the inventive arrangements.The architecture can include a delegate archive 210 associated with oneor more delegates 200 and one or more services 220. The delegate archive210 can include a top level definition specifying how all delegates 200behave in the delegate archive 210.

Each instance of the delegates 200 can encapsulate information regardingthe delegate such as the name of the delegate, the name of the interfaceimplemented by the delegate and the name of the factory able to producethe delegate. In contrast, each instance of the service 220 canencapsulate a service name and a service type, referring to one or moreservice type implementations 230A . . . 230 n, for instance a beanservice or a plain object service. In the case of a bean service,information required to remotely access a bean associated with theservice can be encapsulated within the bean service.

Notably, each instance of the delegates 200 can include a reference toone or more behaviors 250 and one or more profiles 240. Each of thebehaviors 250 can encapsulate a behavior name. Moreover, each of thebehaviors 250 can reference one or more caches 260, and one or moremethods 270. In respect to the methods 270, each of the methods 270 canencapsulate information regarding an associated behavior attribute,whether or not the method can support the associated behavior attribute,a set of input parameters, and a method name. Importantly, each of themethods 270 further can include an associated one of the services 220.

In accordance with the present invention, the delegate 200 can beassociated with one or more profiles 240 and the delegate 200 caninclude an instance of a profile 240. Each instance of the profile 240can include a profile name, a flag indicating whether instance of theprofile 240 is a default instance, and one or more instances of abehavior 250. The instances of the behavior 250 can include a serverhosted behavior, a client hosted but offline behavior, and a clienthosted and client online behavior.

In a preferred aspect of the invention, An extensible markup language(“XML”) descriptor file located in the META-INF directory of an archivefile can define how the each methods of a delegate behave and how thedelegate can be bound to services for each specified environment.Through the use of a dynamic proxy, a module can dispatch calls to thedelegate for the appropriate service. Yet, from the perspective of theclient, a single object has been called through a single interface,regardless of from where the code for the delegate has been invoked andhow the code for the delegate has been invoked.

To load the descriptor in an archive file, an API call can be made asfollows: <delegate interface> delegate = (<delegate interface>)DelegateProxy.newInstance (new ServiceEnvironment( ), <delegate factoryclass>.class);

For example, the call can include: public MyServiceDelegate create(ServiceEnvironment environment) {  return (MyServiceDelegate)DelegateFactory.INSTANCE.create  (environment,MyServiceDelegateFactoryImpl.class); }

Based upon the exemplary embodiment, the delegate factory class shouldbe disposed in the same archive as the descriptor file and should bedefined in the descriptor file. Appendix A includes a pseudo-listing ofan exemplary descriptor file. The exemplary descriptor file can includea delegate definition element as a top level element which can include aservice element and a delegates element. The services element cancontain all definitions for all of the services available for use by thedelegate. This element must contain at least one service. Preferably,there are at least two types of supported services: an enterprise beanservice and a plain object service.

The enterprise bean service can include as sub-elements, a service name,a specification of whether the service is located in a remote server orin the client bean container, a remote naming and directory interfacename for the service, a remote home interface of the service, a remoteinterface of the enterprise bean service, a local naming and directoryinterface name for the service, a local home interface of the service,and a local interface of the enterprise bean service. The plain objectservice, by comparison, can include as sub-elements, a service name, akey for looking up the implementation in application properties, and aninterface implemented by the plain object service implementation.

The delegates portion of the descriptor file can include informationabout the delegates which can include at least one delegate. Notably,there can be at least one delegate per delegate factory defined in thearchive file. As sub-elements, the following can be specified in thedelegates portion of the descriptor file: at least one delegate whichcan include a delegate name, a class name of the factory used for thedelegate to associate a factory to the delegate, an interface exposed bythe delegate, and one or more behaviors. The behaviors can include abehavior that can be bound to state. The behaviors can include a nameand a method element defining how methods are bound to services, if atall.

The following elements are sub-elements of the method attribute in thedescriptor file: a method name which can include wildcard values, methodparameters, and the path to the parameters, and a service name definedin the <services> element to be used for the method. A behaviorattribute also can be included which can specify which values aresupported or not supported. By supported it is meant that the method isavailable for invocation. Conversely, by not supported it is meant thatthe method is not available for invocation. Finally, a cache sub-elementcan be included which can describe how the return value for the methodcan be cached.

A profile element also can be specified in the descriptor file. Theprofile element can specify one or more profiles and at least oneprofile can be defined as the default profile. Profiles can be used todescribe a profile for how the delegate behaves given an environmentfrom which the delegate is invoked. Aside from a profile name, a profilecan include as sub-elements a behavior name defined in the <behaviors>element which is used when the delegate is invoked in a particularenvironment. For instance, a <serverBehavior> behavior is a behavior tobe used when the delegate is invoked on the server. Similarly, the<clientOfflineBehavior> is the behavior used when the delegate isinvoked on the client and is in an offline state. Finally, the<clientOnlineBehavior> sub-element can indicate a behavior to be usedwhen the delegate is invoked on the client and is in an online state.

The present invention can be realized in hardware, software, or acombination of hardware and software. An implementation of the methodand system of the present invention can be realized in a centralizedfashion in one computer system, or in a distributed fashion wheredifferent elements are spread across several interconnected computersystems. Any kind of computer system, or other apparatus adapted forcarrying out the methods described herein, is suited to perform thefunctions described herein.

A typical combination of hardware and software could be a generalpurpose computer system with a computer program that, when being loadedand executed, controls the computer system such that it carries out themethods described herein. The present invention can also be embedded ina computer program product, which comprises all the features enablingthe implementation of the methods described herein, and which, whenloaded in a computer system is able to carry out these methods.

Computer program or application in the present context means anyexpression, in any language, code or notation, of a set of instructionsintended to cause a system having an information processing capabilityto perform a particular function either directly or after either or bothof the following a) conversion to another language, code or notation; b)reproduction in a different material form. Significantly, this inventioncan be embodied in other specific forms without departing from thespirit or essential attributes thereof, and accordingly, referenceshould be had to the following claims, rather than to the foregoingspecification, as indicating the scope of the invention.

1. A method for delegating an invoked action in an enterpriseapplication, the method comprising the steps of: determining anenvironment from which the action has been invoked; selecting a behaviorfor use which corresponds to said environment; and, delegating saidaction to said selected behavior for processing in the enterpriseapplication.
 2. The method of claim 1, wherein said determining stepcomprises the step of determining whether the action has been invoked ina server.
 3. The method of claim 1, wherein said determining stepcomprises the step of determining whether the action has been invoked inan online client.
 4. The method of claim 1, wherein said determiningstep comprises the step of determining whether the action has beeninvoked in an offline client.
 5. The method of claim 1, wherein saidselecting step comprises the step of mapping said determined environmentto a corresponding behavior specified by a profile in a descriptor filein an archive hosting a delegate for the action.
 6. The method of claim1, wherein said delegating step comprises the step of delegating theaction to a method associated with said selected behavior, said methodreferencing a service for said determined environment.
 7. The method ofclaim 1, wherein said delegating step comprises the step of delegatingthe action to a method associated with said selected behavior, saidmethod referencing a service for said determined environment.
 8. Themethod of claim 1, further comprising the step of performing one ofpre-processing and post-processing of a result produced by said selectedbehavior.
 9. An environment aware business delegate archive comprising:at least one delegate and at least one service; said delegatereferencing at least one behavior corresponding to a particularenvironment specified in an associated referenced profile; said servicedefining an interface to at least one environment specific service; saidbehavior having at least one association with a method corresponding tosaid at least one environment specific service.
 10. The archive of claim9, further comprising a descriptor file specifying different bindings ofdelegates to different behaviors based upon different invocationenvironments.
 11. A machine readable storage having stored thereon acomputer program for delegating an invoked action in an enterpriseapplication, the computer program comprising a routine set ofinstructions which when executed by a machine cause the machine toperform the steps of: determining an environment from which the actionhas been invoked; selecting a behavior for use which corresponds to saidenvironment; and, delegating said action to said selected behavior forprocessing in the enterprise application.
 12. The machine readablestorage of claim 11, wherein said determining step comprises the step ofdetermining whether the action has been invoked in a server.
 13. Themachine readable storage of claim 11, wherein said determining stepcomprises the step of determining whether the action has been invoked inan online client.
 14. The machine readable storage of claim 11, whereinsaid determining step comprises the step of determining whether theaction has been invoked in an offline client.
 15. The machine readablestorage of claim 11, wherein said selecting step comprises the step ofmapping said determined environment to a corresponding behaviorspecified by a profile in a descriptor file in an archive hosting adelegate for the action.
 16. The machine readable storage of claim 11,wherein said delegating step comprises the step of delegating the actionto a method associated with said selected behavior, said methodreferencing a service for said determined environment.
 17. The machinereadable storage of claim 11, wherein said delegating step comprises thestep of delegating the action to a method associated with said selectedbehavior, said method referencing a service for said determinedenvironment.
 18. The machine readable storage of claim 11, furthercomprising the step of performing one of pre-processing andpost-processing of a result produced by said selected behavior.